Modelling of the WWER-440 fuel rod behaviour under operational conditions with the PIN-micro code

Abstract

Two real WWER-440 fuel rod cases calculated with the PIN-micro and TRANSURANUS codes are presented. The main features and models incorporated in the codes are briefly described. A combination of mean values of the fuel rod geometric and technological parameters is chosen as a representative case for the calculations. The results obtained by the simple quasi-steady state PIN-micro code, developed on the base of GAPCON-THERMAL-2 and verified against WWER operational and experimental data, prove the existence of the typical WWER-440 safety margins for the fuel temperature and the gas pressure for the whole period of operation. First results obtained by the advanced fuel rod performance code TRANSURANUS, verified against a large number of available fuel rod experimental data (except for WWER fuel rods), are compared with the PIN-micro ones. For this purpose the code is modified through incorporation of some WWER-specific fuel and cladding properties and correlations. The comparison of the results of both codes shows a reasonable compliance, as well as logical discrepancies at very low and intermediate burnups.